US 5,289,225 AGranted

Photometering apparatus of camera for variably weighting different areas of an image area

AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha

InventorIsamu Hirai

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Abstract

A photometering apparatus for a camera is provided that includes a split type photometering device for measuring the luminance of an object to be photographed and in which an image area is divided into a plurality of object luminance measuring zones, an automatic focusing device which selectively has a focus lock mode in which once an object within an object distance measuring is in focus, the focus is maintained, and a non-focus lock mode in which the focus is continuously adjusted within the object distance measuring zone. The photometering apparatus also includes an exposure controller which varies the weighting of the luminance signals of the object luminance measuring zones of the split type photometering device, in order to calculate an exposure value, depending on the selection of the focus lock mode or the non-focus lock mode.

Claims10

Dependent claims

A photometering apparatus for a camera, comprising:

a split type photometering device for measuring the luminance of an object to be photographed, in which a picture plane is divided into a plurality of object luminance measuring zones;
an insensible band which photoelectrically isolates said object luminance measuring zones from one another;
an automatic focusing device which selectively has a focus lock mode in which once an object within an object distance measuring zone is in focus, the focus is maintained, and a non-focus lock mode in which the focus is continuously adjusted within said object distance measuring zone;
and,
exposure control means to vary the weighting of the luminance signals of said object luminance measuring zones of said split type photometering device in order to calculate an exposure value, depending on the selection of said focus lock mode or said non-focus lock mode;
wherein said exposure control means further comprises means for varying the weighting of the luminance signals between operations solely in said focus lock mode, when the luminance difference between outputs from a first photometering zone between a first photometering operation and a second photometering operation is greater than a predetermined value.

3 more elements

A photometering apparatus for a camera, comprising:

a first photometering zone corresponding to the center of a rectangular image area;
a second photometering zone which contains points located at the intersection of a first pair of lines which equally divide a major side of said rectangular image area into three segments and a line normal to said first pair of lines, on which the center point of said image area is located, and points located at the intersection of a second pair of lines which equally divide a minor side of said rectangular image area into three segments and a line normal to said second pair of lines, also on which the center point of said image area is located;
a third photometering zone corresponding to a peripheral area of said image area;
and
arithmetic operating means for calculating an exposure value in accordance with output from said first, second and third photometering zones;
wherein said arithmetic operating means performs different operations when, in a focus lock mode, the luminance difference between the outputs from said first photometering zone between a first photometering operation and a second photometering operation is greater or less than a predetermined value.

3 more elements

Dependencies are inferred from the claim text.